Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C08L23/0869—Acids or derivatives thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/447—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from acrylic compounds
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/448—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from other vinyl compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/24—Acids; Salts thereof
  • C08K3/26—Carbonates; Bicarbonates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2314/00—Polymer mixtures characterised by way of preparation
  • C08L2314/06—Metallocene or single site catalysts
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds

Definitions

• the present invention relates to a flame retardant polymer composition, to a wire or cable comprising said flame retardant polymer composition, and to the use of said composition for the production of a layer, preferably a jacketing layer of a wire or cable.
• a typical electrical power cable or wire generally comprises one or more conductors in a cable core, which is surrounded by one or more insulation layers or sheaths of polymeric material.
• the core is typically copper or aluminium but it may also be nonmetallic, surrounded by a number of different polymeric layers, each serving a specific function, e.g. a semi-conducting shield layer, an insulation layer, a metallic tape shield layer and a polymeric jacket.
• Each layer can provide more than one function.
• low voltage wire or cable are often surrounded by a single polymeric layer that serves as both an insulating layer and an outer jacket, while medium to extra-high voltage wire and cable are often surrounded by at least separate insulating and jacket layers.
• a power cable may for example be surrounded by a first polymeric semiconducting shield layer, a polymeric insulating layer, a second polymeric semiconducting shield layer, a metallic tape shield, and a polymeric jacket.
• polymeric materials have been utilized as electrical insulating and semiconducting shield materials for power cables. Such polymeric materials in addition to having suitable dielectric properties must also be enduring and must substantially retain their initial properties for effective and safe performance over many years of service. Such materials have also to meet stringent safety requirements as laid down in international standards. In particular, single cable, or bundle of cables, must not bum by itself or transmit fire; the combustion gases of a cable must be as harmless as possible to humans, the smoke and combustion gases formed must not obscure escape routes or be corrosive.
• Flame retardants are chemicals used in polymers that inhibit or resist the spread of fire.
• compounds containing halides were first added to the polymer.
• these compounds have the disadvantage that upon burning, hazardous and corrosive gases like hydrogen halides are liberated.
• the polymer composition according to the present invention has the advantage of having essentially no emission of harmful gases and combining excellent flame retardant properties, very good mechanical properties, good processability, good flexibility and pressure deformation resistance.
• the flame retardant polymer composition according to the invention comprises:
• the ethylene copolymer (A) is an ethylene methacrylate copolymer (EMA).
• the ethylene copolymer (B) comprises co-monomer units derived from C 4 to C 12 ⁇ -olefin, more preferably from Cg to C 12 ⁇ -olefin.
• the ⁇ -olefin is octene.
• the ethylene copolymer (B) is present in an amount between 3 and 20 wt% of the total polymer composition, preferably between 7 and 15 wt%.
• the halogen-free mineral filler (C) has preferably a decomposition temperature above 200°C.
• the maleic anhydride modified ethylene homo-or copolymer (D) is preferably present in the composition in an amount of 1 to 10 wt% of the total polymer composition.
• the co-monomer of the maleic anhydride modified ethylene homo- or copolymer (D) is an ⁇ -olefin.
• maleic anhydride units are grafted onto an ethylene homo or copolymer backbone.
• the ethylene homo-or copolymer backbone is a low density polyethylene, linear low, medium or high density polyethylene and very low density polyethylene
• the composition may further comprising an ethylene copolymer (E) having a density between 0.912 and 0.940 g/cm 3 .
• the ethylene copolymer (E) comprises comonomer units derived from C 3 to C 12 ⁇ -olefin.
• the ethylene copolymer (E) is present in an amount between 1 and 7 wt%, more preferably 2 to 5 wt% of the total polymer composition.
• the retardant polymer composition claims feature a hot pressure resistance/indentation below 50%.
• the present invention is directed to a wire or cable comprising the composition described above.
• the wire or cable comprises a jacketing layer comprising the composition described above.
• said wire or cable is used in a building construction.
• the present invention is directed to the use of the composition described above in the production of a layer of a wire or a cable.
• the present invention is also directed to a process for producing the composition described above, said process comprising compounding the polymer composition at a temperature up to 235°C.
• the flame retardant polymer composition according to the present invention comprises an ethylene copolymer (A) comprising polar groups selected from the group consisting of acrylic acids, methacrylic acids, acrylates, methacrylates, acetates and vinyl acetates. More preferably, the polar groups are selected from the group consisting of alkyl acrylates, alkyl methacrylates, and vinyl acetates. Even more preferably, the polar groups are selected from the group consisting of C 1 - to C 6 -alkyl acrylates, C 1 - to C 6 -alkyl methacrylates, and vinyl acetates. Still more preferably, the polar groups are selected from the group consisting of C 1 - to C 4 -alkyl, such as methyl, ethyl, propyl or butyl acrylates or vinyl acetate.
• A ethylene copolymer
• polar monomer units may be selected from the group of alkylesters of (meth)acrylic acid, such as methyl, ethyl and butyl(meth)acrylate and vinylacetate.
• (A) is an ethylene acrylate copolymer
• (A) is an ethylene methyl acrylate copolymer (EMA).
• the ethylene copolymer (A) comprising polar groups is prepared by copolymerizing ethylene and at least a polar comonomer mentioned above.
• it may also be produced by grafting the polar group onto the homo- or copolymer backbone.
• the polar copolymer is prepared by copolymerizing ethylene with a polar comonomer, this is preferably effected in a high pressure process resulting in low density ethylene copolymer or in a low pressure process in the presence of any suitable catalyst, for example a chromium, Ziegler-Natta or single-site catalyst.
• component (A) has a polar comonomer content from 10 to 35 wt%, more preferably from 15 to 30 wt% or even more preferably from 15 to 25 wt%.
• component (A) has a melt flow rate MFR (190°C, 2.16 kg) of 0.1 to 50 g/10 min, more preferably of 0.2 to 10 g/10 min and most preferably of 0.2 to 3.0 g/10 min.
• MFR melt flow rate
• the amount of component (A) is from 5 to 40 wt.% of the total polymer composition, more preferably is from 15 to 25 wt.% and most preferably is from 17 to 22 wt.%.
• the polymer composition according to the invention further comprises a single site catalyst prepared ethylene copolymer (B) having a density between 0.860 and 0.910 g/cm 3 .
• the polyethylene (B) has a density between 0.870 and 0.905 g/cm 3 , more preferably between 0.875 and 0.900 g/cm 3 .
• the ethylene copolymer (B) may be prepared in a low pressure process through the use of a class of highly active olefin catalysts known as metallocenes, preferably those based on group IV B transition metals, zirconium, titanium and hafnium.
• metallocenes preferably those based on group IV B transition metals, zirconium, titanium and hafnium.
• the ethylene copolymer (B) conveniently comprises comonomer units derived from C 4 to C 12 ⁇ -olefin, more preferably from C 8 to C 12 ⁇ -olefin. Even more preferably the comonomer units of ethylene copolymer (B) consist of comonomer units derives from one or more C 4 to C 12 ⁇ -olefin, more preferably from C 8 to C 12 ⁇ -olefin. In one embodiment of the present invention the ⁇ -olefin is octene. By using octene the melting point of the copolymer (B) is increased and the stickiness decreased.
• the polyethylene (B) has a melting point of at least 65°C and below 110°C.
• the polyethylene (B) is preferably present in an amount between 3 and 20 wt% of the total polymer composition, preferably between 7 and 15 wt%.
• the inventive flame retardant polymer composition further comprises a halogen-free mineral filler (C) comprising a huntite and/or a hydromagnesite.
• C halogen-free mineral filler
• Huntite CaMg 3 (CO 3 ) 4 and and hydromagnesite Mg 5 (CO 3 ) 4 (OH) 2 .4H 2 O are classified as carbonate minerals having no simple metal hydroxide structures like other mineral flame-retardants.
• Fraction (C) is preferably coated.
• the specific filler used in the composition of the invention allows compounding the polymer composition up to 235°C, which give a much larger processing window compared to the well know filler Al(OH) 3 which has a maximum compounding temperature of 180°C.
• the halogen-free mineral filler (C) comprises a mixture of at least 20 wt% of the total polymer composition of huntite and hydromagnesite and even more preferably the halogen-free mineral filler (C) comprises a mixture of at least 20 wt% of the total polymer composition of huntite and at least 55 wt% of the total polymer composition of hydromagnesite.
• the mineral filler is preferably present in the composition of the present invention in an amount of 30 to 80 wt%, preferably of 45 to 70 wt% and more preferably of 55 to 67 wt% of the total polymer composition.
• the flame retardant polymer composition according to the invention further comprises a maleic anhydride modified ethylene homo- or copolymer (D) as coupling agent.
• component (D) may be produced by means of copolymerization of ethylene, maleic anhydride units and, optionally, further comonomers, or by grafting the maleic anhydride units onto ethylene homo- or copolymer backbone. More conveniently, maleic anhydride units are grafted onto the ethylene homo or copolymer backbone.
• suitable co-monomers may comprise polar groups selected from the group consisting of acrylic acids, methacrylic acids, acrylates, methacrylates, acetates and vinyl esters or ⁇ -olefins.
• the co-monomer is an ⁇ -olefin.
• the ⁇ -olefin is selected from the group consisting of C 3 to C 12 ⁇ -olefin, more preferably from C 4 to C 8 ⁇ -olefin.
• the ethylene homo- or copolymer backbone is a low density polyethylene, linear low, medium or high density polyethylene and very low density polyethylene.
• the ethylene homo- or copolymer backbone is a low density polyethylene and mostly preferred is a linear low density polyethylene.
• component (D) is produced by means of copolymerization of ethylene, maleic anhydride units and further comonomers
• said further comonomers may also comprise polar groups selected from the group consisting of acrylic acids, methacrylic acids, acrylates, methacrylates, acetates and vinyl esters or ⁇ -olefins.
• the co-monomer is an ⁇ -olefin.
• the ⁇ -olefin is selected from the group consisting of C 3 to C 12 ⁇ -olefin, more preferably from C 4 to C 8 ⁇ -olefin.
• Preferred densities of component (D) are densities not higher than 930 g/cm 3 .
• Component (D) preferably has a density between 0.890 and 0.930 g/cm 3 , more preferably between 0.900 and 0.920 g/cm 3 .
• the amount of units derived from maleic anhydride in the maleic anhydride modified ethylene homo- or copolymer is from 0.5 to 48 wt%, more preferably from 1 to 5 wt%, most preferably from 2 to 4 wt%
• the maleic anhydride modified ethylene homo- or copolymer (D) is present in the flame retardant polymer composition in an amount up to 10 wt.%, more preferably in an amount of 1 to 8 wt.%, and most preferably in an amount of 2.0 to 6 wt.% of the total polymer composition.
• the maleic anhydride modified ethylene homo- or copolymer (D) preferably has a melt flow rate MFR (190°C, 2.16 kg) of 0.1 to 5.0 g/10 min, more preferably of 0.5 to 4.0 g/10 min, and most preferably of 1.0 to 2.5 g/10 min.
• the polymer composition of the invention may further comprises an ethylene copolymer (E) having a density between 0.912 and 0.940 g/cm 3 , preferably between 0.912 and 0.930 g/cm 3 and more preferably between 0.915 and 0.920 g/cm 3 .
• the ethylene copolymer (E) comprises comonomer units derived from C 4 to C 8 ⁇ -olefin, more preferably the comonomers units consist of one or more comonomer units derived from C 4 to C 8 ⁇ -olefin.
• the ethylene copolymer (E) is prepared by low pressure polymerization.
• the ethylene copolymer (E) may be prepared in a low pressure polymerization process through the use of a class of highly active olefin catalyst known as metallocenes, preferably, those based on group IV B transition metals, such as zirconium, titanium and hafnium.
• the ethylene copolymer (E) has a tensile strength of at least 8MPa.
• a preferred ethylene copolymer (E) is linear low density polyethylene.
• the ethylene copolymer (E) is present in an amount between 1 and 7 wt% of the total polymer composition, more preferably 2 to 5 wt%.
• composition of the present invention may further comprise a processing aids and/or a drying agent.
• drying agents are for example, silica gel, CaO, CaSO 4 , molecular sieves.
• CaO is employed as drying agent.
• a drying agent is present in the composition in an amount of 0.01 to 2 wt%, more preferably between 0.05 to 1 wt%, most preferably between 0.1 to 0.7 wt% of the total polymer composition.
• Suitable processing aids are the ones well known in the art, such as for example, low molecular weight polypropylenes.
• a metallocene catalyst based polypropylene wax is used as processing aid.
• a processing aid is present in the composition in an amount of 0.01 to 10 wt%, more preferably between 0.05 to 7 wt%, most preferably between 1 to 5 wt% of the total polymer composition.
• inventive compositions may also contain additional conventional additives such as, for example, antioxidants and UV stabilizers, in small amounts.
• Said additives are usually present in an amount of not more than 5.0 wt%, preferably not more than 3.0 wt% and more preferably not more than 1.0 wt% of the total composition.
• antioxidant sterically hindered or semi-hindered phenols, aromatic amines, aliphatic sterically hindered amines, organic phosphates, thio compounds, and mixtures thereof, may be used.
• the flame retardant composition may be used in many diverse applications and products.
• the compositions can for example be moulded, extruded or otherwise formed into mouldings, sheets and fibers.
• a multilayered article can be prepared wherein at least one layer comprises said polymer composition.
• the multilayered article is a wire or cable.
• the wire or cable comprises a jacketing layer comprising the composition described above.
• said wire or cable is used in a building construction.
• a wire or cable is defined to be a cable transferring energy operating at any voltage.
• the voltage applied to the cable can be alternating (AC), direct (DC), or transient (impulse).
• the multilayered article is a wire or cable operating at voltages lower than 1 kV, preferably the multilayered article is a cable to be used in building constructions.
• the flame retardant polymer composition according to the invention is preferably prepared by mixing together the components by using any suitable means such as conventional compounding or blending apparatus, e.g. a Banbury Mixer, a 2-roll rubber mill or a twin screw extruder, Buss co-kneader, etc.
• suitable means such as conventional compounding or blending apparatus, e.g. a Banbury Mixer, a 2-roll rubber mill or a twin screw extruder, Buss co-kneader, etc.
• the compounding temperature is typically in a range of 120°C to 200°C and not higher to avoid decomposition of the flame retardant filler, the polymer composition of the present invention allows reaching a compounding temperature up to 235°C.
• the flame retardant polymer composition according to the invention is preferably extruded to form a flame retardant layer of a wire or cable. This is preferably done at a line speed of at least 20 m/min, more preferably at least 50 m/min.
• the pressure used for the extrusion is 50 to 500 bar.
• the polymer composition can be applied onto the metallic conductor and/or at least one coating layer thereof, e.g. a semiconductive laver or insulating layer.
• Test specimens prepared with the flame retardant polymer composition of the present invention shows good mechanical properties.
• Said specimens feature at the same time good flame retardancy, e.g. in the limiting oxygen index (LOI).
• LOI limiting oxygen index
• the LOI which is a measure of ease of extinction, is a measure of a product's flame resistance. LOI is a measure of the minimum oxygen concentration of an O 2 /N 2 mixture required to sustain combustion for a minimum of 3 minutes or not propagate more than 5 cm from the top of the test specimen.
• a high LOI value means that a high percentage of oxygen is needed to sustain combustion, i.e. the compound has a good flame resistance.
• the LOI value for a flame retardant composition should be at least 22 and higher values are desirable.
• the composition of the present invention feature LOI value higher than 28%, or higher than 30%.
• Test specimens prepared with the flame retardant polymer compositions of the present invention surprisingly also show excellent pressure resistance with indentation value well below 50%, preferably below 30%, when undergoing a hot pressure test for 6h at 80°C.
• the melt flow rate MFR 2 was measured in accordance with ISO 1133 at 190°C and a load of 2.16 kg or at or 150°C and a load of 21.6 kg.
• LOI was determined using a Stanton Redcroft FTA Flammability Unit by the US standard ASTM D 2863-77 and the ISO 4589.
• test specimen of the compound to be evaluated is ignited in an atmosphere of a mixture of nitrogen and oxygen.
• the content of oxygen in the N 2 /O 2 mixture is gradually decreased until the specimen stops burning.
• the percentage of O 2 in the N 2 /O 2 mixture constitutes the compounds LOI value.
• the LOI results are based on approximately 10 test specimens of dimension "150 x 6 mm". These are stamped out from a 3 mm thick plate pressed in a Collins press (low pressure (20 bar) at 150°C during one minute followed by high pressure (200 bar) during five minutes at the same temperature). Cooling rate was 10° C/minute under high pressure. The compound is immediately taken from the mixer to the press.
• Tensile strength and elongation at break was determined according to ISO527-2.
• Dumb-bell test pieces were prepared according to ISO 527-2, Type 5A, from 2.0 mm thick compression moulded plaques.
• the compounds were extruded into thin tapes, using a Brabender Plasti-corder extruder with a film nozzle.
• the tape had a thickness of 1.5 mm.
• the temperature profile used was either 160/170/180°C or 180/190/200°C.
• the extruder speed was 50 rpm.
• the extruder tapes were used as material for the compression moulding of plaques.
• the tapes were stacked in a frame.
• the thickness of the plaque depends on the consecutive test to be executed (tear strength and pressure test: 1mm; tensile properties: 2 mm).
• the compounds (tapes) were pressed into plaques in a Collin press at 200 bar at a temperature of 170°C, with the exception of comparative example 2 which was pressed at a temperature of 180°C, during five minutes. Cooling rate was 15°C/minute under high pressure.
• the direction of the test species was parallel to the original orientation of the extruded tapes.
• the elongation at break and tensile strength was conducted at 23°C with an elongation rate of 50 mm/min.
• the pressure test was conducted according to IEC 60811-3-1 at a temperature of 80°C for 6 hours.
• a 3 mm wire was positioned under the compression moulded plaques prepared according to the description under section c) above.
• the densities were measured according to ISO 1183 on compression moulded specimens.
• the melting temperatures indicated in Table 1 and 2 are taken from the datasheets of the respective compounds.
• Example 1 EBA (ethylene butyl acrylate copolymer) is used as component (A) instead of the EVA (ethylene methyl acrylate copolymer) of Examples 2-4.
• the composition of Example 3 has a higher amount of EVA and a lower amount of VLDPE (B), whereas a maleic anhydride grafted linear low density polyethylene Maleic acid anh. Grafted PE) (D) and the coated Huntite/Hydromagnesite filler is present in the same amounts in all the compositions.
• VLDPE stands for very low density ethylene copolymer and corresponds to component (B.)
• VLDPE is an ethylene octene copolymer.
• LLDPE stands for linear low density ethylene copolymer and corresponds to component (E).
• LDPE is a C 4 Ziegler Natta linear low density ethylene copolymer.
• a metallocene catalyst based propylene wax (PP wax) is used as processing aid.
• Calcium oxide (CaO) is used as drying agent and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is used as antioxidant (AO).
• Table 1 Type Product Melting Temp. °C Density g/cm3 EX1 wt% EX2 wt% EX3 wt% EX4 wt% EMA Elvaloy 1125 DuPont 90 0.944 18 20 19 EBA Lotryl 17BA 04 Arekma 91 0.93 18 VLDPE Exact 8203 ExxonMobil 72 0.882 11 11 9 11 LLDPE LL1004YB ExxonMobil 121 0.918 2.50 2.50 2.50 2.50 2.50 Maleic anh.
• compositions of the Comparative Examples the same amounts of coated Huntite/Hydromagnesite filler and component B are used as in the compositions of the Examples.
• Three kinds of EBA ethylene butyl acrylate copolymer
• component (A) ethylene butyl acrylate copolymer
• component (A) ethylene butyl acrylate copolymer
• component (A) ethylene butyl acrylate copolymer
• a combination of EBA and EVA is used.
• Maleic anhydride grafted EVA ethylene methacrylate copolymer
• anhydride grafted EBA ethylene butyl acrylate copolymer
• PE polyethylene
• VLDPE stands for very low density ethylene copolymer and corresponds to component (B.)
• VLDPE is an ethylene octene copolymer. All the comparative examples include a VLDPE, with the exception of C5.
• LLDPE and LDPE correspond to component (E).
• LLDPE stands for linear low density ethylene copolymer and it is a C 4 Ziegler Natta linear low density ethylene copolymer.
• LDPE stands for low density polyethylene and it is a high molecular weight low density polyethylene.
• Comparative examples C1-C3 show good flame retardant properties but bad mechanical properties and unsatisfactory hot pressure/indentation test values.
• Comparative Example 4 features good flame retardant properties, good tensile strength but still unsatisfactory elongation at break and hot pressure/indentation test values.
• Comparative Example 5 features good flame retardant properties, good tensile strength, good hot pressure/indentation test values but unsatisfactory elongation at break.
• Table 3 Property C1 C2 C3 C4 C5 EX1 EX2 EX3 EX4 Density [g/cm3] 1494 1485 1475 1493 1480 1480 1500 1502 1500 MFI(150°C/21.6) [g/10min] 12.3 8.6 8.9 16.5 6.3 8.2 4.9 5.5 5.1 Shore A 97 95 96 95 96 94 95 96 97 Shore D 50 50 49 49 53 53 49 50 50 LOI [%O 2 ] 30 31 33 35 38 37 31 36 36
• the polymer compositions of the invention feature the required flame retardant properties while having the desired elongation and indentation properties.

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